Regulatory Matters (Schedule of Components of the Annual Rate Increase Requested) (Details) - 2016 Electric Rate Case [Member] - Consumers Energy Company [Member] $ in Millions	1 Months Ended
Mar. 31, 2016 USD ($)
Annual rate increase requested	$ 225
Investment In Rate Base [Member]
Annual rate increase requested	161
Operating And Maintenance Costs [Member]
Annual rate increase requested	21
Gross Margin [Member]
Annual rate increase requested	17
Cost Of Capital [Member]
Annual rate increase requested	15
Working Capital [Member]
Annual rate increase requested	$ 11

Amount of public utility's requested rate increase (decrease) with regulatory agency.

No definition available.

Name:	us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration